I've never changed the battery, and yes I bought the car used 2 yrs ago.
One other thing I can say, all this started to happened when I was leaning on my trunk and someone pressed the release trunk button on my FOB. Ever since then I have been having issues with the car. I don't know it that might do all these things.
I tried to leave the gym last night and I couldn't get the car to crank but I had full power in the car. It didn't sound like the car was even trying to turn.
Who knows I know I have a something electrical wrong, I just don't know where to find it. Maybe you're right I should take to a dealer to get it looked at, only if I could turn it on.